I'm a little short on details, because my brother borrowed my car and that's when it started happening.

First, I make a long haul drive (4 hours) back home late at night. On the way back I notice a few down shifts from 5th to 4th ended with the clutch slipping like crazy (RPM at a level that should have me doing 100mph, when I'm doing 60mph).
I thought my clutch was going out. Who knows, maybe it is, but I'm hoping it's not

Than my brother borrows the car and says that while driving he couldn't get it into gear. He also said that the Clutch at one point stuck to the floor and wouldn't come back up.
I take the car for a spin, experience nothing for a few minutes, than sure enough, the clutch stuck to the ground. Additionally, even though the clutch was floored, it was still kind of catching.

Internet says a clutch that won't disengage is likely to be either the master or slave clutch cylinders, IF
1. The system has fluid
2. There isn't air in there

Now the problem came on in a matter of hours, and isn't consistent. I need (or strongly desire) to drive the car another 6 hours this weekend. The cylinders are relatively cheap, so if I don't find anything that points away from them tonight, I might just overnight the parts.

Thoughts? Any chance my slipping clutch could be related? When the cylinders go, does it not properly engage as well as disengage?

QuoteEarendil
Master or slave I don't know. Or maybe air, but I doubt it.

I'm a little short on details, because my brother borrowed my car and that's when it started happening.

First, I make a long haul drive (4 hours) back home late at night. On the way back I notice a few down shifts from 5th to 4th ended with the clutch slipping like crazy (RPM at a level that should have me doing 100mph, when I'm doing 60mph).
I thought my clutch was going out. Who knows, maybe it is, but I'm hoping it's not

Than my brother borrows the car and says that while driving he couldn't get it into gear. He also said that the Clutch at one point stuck to the floor and wouldn't come back up.
I take the car for a spin, experience nothing for a few minutes, than sure enough, the clutch stuck to the ground. Additionally, even though the clutch was floored, it was still kind of catching.

Internet says a clutch that won't disengage is likely to be either the master or slave clutch cylinders, IF
1. The system has fluid
2. There isn't air in there

Now the problem came on in a matter of hours, and isn't consistent. I need (or strongly desire) to drive the car another 6 hours this weekend. The cylinders are relatively cheap, so if I don't find anything that points away from them tonight, I might just overnight the parts.

Thoughts? Any chance my slipping clutch could be related? When the cylinders go, does it not properly engage as well as disengage?

QuoteEarendil
Master or slave I don't know. Or maybe air, but I doubt it.

I'm a little short on details, because my brother borrowed my car and that's when it started happening.

First, I make a long haul drive (4 hours) back home late at night. On the way back I notice a few down shifts from 5th to 4th ended with the clutch slipping like crazy (RPM at a level that should have me doing 100mph, when I'm doing 60mph).
I thought my clutch was going out. Who knows, maybe it is, but I'm hoping it's not

Than my brother borrows the car and says that while driving he couldn't get it into gear. He also said that the Clutch at one point stuck to the floor and wouldn't come back up.
I take the car for a spin, experience nothing for a few minutes, than sure enough, the clutch stuck to the ground. Additionally, even though the clutch was floored, it was still kind of catching.

Internet says a clutch that won't disengage is likely to be either the master or slave clutch cylinders, IF
1. The system has fluid
2. There isn't air in there

Now the problem came on in a matter of hours, and isn't consistent. I need (or strongly desire) to drive the car another 6 hours this weekend. The cylinders are relatively cheap, so if I don't find anything that points away from them tonight, I might just overnight the parts.

Thoughts? Any chance my slipping clutch could be related? When the cylinders go, does it not properly engage as well as disengage?

You have more than one problem

The slipping clutch in high gear means it's worn out :sick:

The other symptoms may be due to a worn throw bearing or collapsed pressure plate spring...and/or cylinder problems.

No matter what, you are going to have to separate the motor from the transmission to take care of this

1. Everything is visually okay. No obvious leaks.
2. The clutch is workable, if used quickly.
3. The clutch even if it sticks, can be returned to a normal position and start functioning again.
4. The clutch can often times be pressed down quickly and hold pressure. However if slight pressure is applied to the pedal, it will slowly sink to about half way, NOT disengaging the clutch. At that point, pressing the pedal all the way down does not fully disengage the clutch.

Here is how I've visualized the problem. The cylinder piston is able to leak piston past it's seal. If the piston is pressed quickly, the piston ring/seal enter a portion of the cylinder that does not allow for leaking fluid. If slight pressure is applied, fluid leaks past the piston to the side of the cylinder that shouldn't be seeing fluid. Naturally, if the pedal is forced back by hand, that fluid will return to the proper side of the piston.

With that idea in mind, I drove home. At every stop light and stop sign I quickly clutched and put the car in neutral, and then let out the clutch. I did this instead of holding the clutch down. I felt like I had a little more trouble shifting, but it wasn't bad at all. This got me home with no problems. In fact I would almost think it was fixed, if I wasn't aware of how to reproduce it. It makes sense that my brother would find this issue first, since having less experience with a stick he would be inclined to have the clutch in for longer periods of time, especially when downshifting.

Since I can repro and fix repeatedly, it doesn't strike me as mechanical (okay, so fluid dynamics is mechanical, but you know what I mean). I can get it into a state of "broken" and then back again. Also, the master/slave cylinders appear to be the most likely source of this problem. Also, a slave cylinder cost $25. This has got to be the cheapest cast metal part on this car! And at least the slave cylinder looks about as easy to replace as a fuel filter. Bonus on the repair time. So I'll replace these parts first and see where the car is at.

I'm really hoping that with the fluid on the wrong side of either a cylinder, that the clutch was also not able to fully engage at times, causing clutch slip under force. I had my clutch slip on the highway 3 or so times unintentionally, but was never able to intentionally slip it. It would not surprise me if my clutch disc was worn out, but I'm willing to hold out hope. At the very least I'll hold out for spring

QuoteMichiel 318iS
Or learn to shift without using the clutch. Driving off will happen when starting in 1st gear then, after having stopped the engine from neutral.

Check for signs of an oil leak. If a cylinder is bad and the clutch pedal stays down while the clutch is still fully engaged, you must have leaked some oil. Or just the pressure line is bad.

Doesn't look like it is a bearing or clutch spring failure, as it only happens after a while.

When you says that the pressure line could be bad, can it be bad in a way that doesn't involve leaking? Just curious, since it seemed to be an additional option in your list there above and beyond a leak

If I'm right, the master cylinder leaks into the vehicle interior, hope for you this is not the case. If the slave cylinder leaks, it leaks into the bell housing, which over time will become clear where the bell housing meets the engine.

Whether it is one of the cylinders or the pressure line, you should find a leak somewhere. It doesn't get caught at the other side of the piston and then returns. If it is the slave cylinder, it could take some time before it gets obvious as the oil might get caught by the rotating parts and sprayed all over the bell housing before it starts coming down and leak out of it (depends on the amount of dust in there as well, the more dust, the more it can absorb the oil).

You'll have to take off the transmission anyway to replace the slave cylinder, if the clutch disc is still good, clean it thoroughly, if it's time to replace, replace pressure plate and throw-out bearing as well while you're at it.

QuoteMichiel 318iS
If I'm right, the master cylinder leaks into the vehicle interior, hope for you this is not the case. If the slave cylinder leaks, it leaks into the bell housing, which over time will become clear where the bell housing meets the engine.

Correct. I'm positive the master is not leaking. The slave would obviously be harder to tell, so I can't be sure of that. I can say that the resevoir level is below the point that would keep filling the clutch. So you'd think that if it were leaking a bunch, that after a few pumps I would have pumped the system empty, or at the very least that it would get worse and become non functional in a very short period of time.

Quote
You'll have to take off the transmission anyway to replace the slave cylinder, if the clutch disc is still good, clean it thoroughly, if it's time to replace, replace pressure plate and throw-out bearing as well while you're at it.

Wait, really? I haven't looked real closely, but I was going off of the pelican parts article, which I now see has "E36" in the link, even though it doesn't say it anywhere in the article body or title.
So you're saying the slave is INSIDE the bell housing and there is no way to get to it without removing the transmission?!
As the weather turns to crap here, and my parts car sold, I all ready for my mechanic-vacation for the winter. *sigh*.
Now that I know this, I guess I'll piece together my Bentley manual and take a look. I hate being caught in assumptions...

Actually, perhaps BMW did the slave cylinder two different ways? I found this E30 break down for replacing the slave cylinder that does not involve removing the transmission. I guess the answer to my question is to throw the car up on jacks after I get off work and take a gander

The slave cylinder is mounted on the outside of the bell housing and is easily accessible from underneath the car. There may be some trick bolts in tight spaces but definitely doable without removing the transmission.

While all the pedal action you described does indicate a master or slave problem; the slipping is probably due to a worn friction disk or other mechanical wear.

One other possibility is the yoke, that holds the throw out bearing, may have broken on of it's forks. I remember seeing symptoms like yours described a long time ago on a previous BEN that was eventually tracked down to a broken yoke fork. Unfortunately, transmission removal is the only way to diagnose that

Thanks Peter, I'm feeling a little better
It looks likethe correct course of action is to replace the master and slave and see what kind of results I get. Cheap items, a few hours of work, and replacing failure prone parts is rarely a bad idea!

At the very least if I have multiple issues, I can eliminate the hydraulics and start saving for a new clutch...

QuoteArcheo-peteriX
The slave cylinder is mounted on the outside of the bell housing and is easily accessible from underneath the car. There may be some trick bolts in tight spaces but definitely doable without removing the transmission.

While all the pedal action you described does indicate a master or slave problem; the slipping is probably due to a worn friction disk or other mechanical wear.

One other possibility is the yoke, that holds the throw out bearing, may have broken on of it's forks. I remember seeing symptoms like yours described a long time ago on a previous BEN that was eventually tracked down to a broken yoke fork. Unfortunately, transmission removal is the only way to diagnose that

Well, you can see it anyway, I don't know if you'd call it an easy R&R but one trick is to put the feed line on the slave before you bolt up the slave on the bellhousing (make sure of the line positioning, copy the old one coming off).

Finished the job. I started by just replacing the slave cylinder. When I removed it I noticed the rubber inside was torn to pieces. I didn't think this would translate directly to it being nonfuntional, but I hoped. I bolted it up and attempted to operate the clutch after bleeding. The system was the same. This time I called out a friend and had them watch for bubbles as I pumped the clutch. They saw no bubbles, but they did say that when I pushed the clutch down, that the fluid level rose. This conflicted with my understanding of what the cylinder should be doing, i.e. pushing the fluid down towards the transmission, not up into the reservoir.

So after finding that I did not own an 11mm wrench (let alone a flare wrench) I gave up and canceled my trip. The next day I removed it all quite handily.

The hardest part was reassembly. Getting the Master Cylinder attacked back to the steering column was a real B****, and worse yet was trying to get the reservoir hose pushed into the master cylinder. In fact that connection is still sort of leaking, so I bought a new plastic connector since the old one wasn't looking so great when I inserted it. Still, the clutch functions quite nicely again

Sadly, I can get the clutch to slip, so I am losing it. I had been expecting this for years. There were no records of when the clutch was done last, and with that many miles I was sure it had been replaced once, and would probably being coming around to a 3rd time. Anyone know how faster the E30 clutch will go once it starts showing signs? With the onset of winter I'm hoping that the tires will stop on snow before it slips the clutch, and I'll make it to spring... or at least until my Christmas bonus so I can have someone else do the clutch for me. That would signify the first time a mechanic has touched the car in the 4 years I've owned it to do anything besides change the tires

Maybe I'm just burned out from all the work I did this spring and summer....Whoops, I'm rambling. Tyler out.

Surprised you are having clutch wear that severe to change the clutch more than once in the life of the car. If the clutch slips in fifth gear when accelerating, it is worn out. Otherwise probably not worn out.

I am not surprised. 250.000 miles is quite a lot and if at least one of the previous owners wasn't to good with manual transmissions, or had to make a lot of uphill starts, or has towed a lot of stuff, the clutch would have been replaced at least once.
And at that mileage, just the style of driving can wear a clutch as well (quick launches, a lot of shifts under load, up and down,...).

QuoteMichiel 318iS
I am not surprised. 250.000 miles is quite a lot and if at least one of the previous owners wasn't to good with manual transmissions, or had to make a lot of uphill starts, or has towed a lot of stuff, the clutch would have been replaced at least once.
And at that mileage, just the style of driving can wear a clutch as well (quick launches, a lot of shifts under load, up and down,...).

Aye. There were 4 previous owners before me, and I haven't exactly driven it like I was trying to make the clutch last forever. I wasn't too rough, but... well you know. Also, I live in a very hilly area. Work is at 100 feet MSL, Town at 800 MSL, and my previous house at 2000 MSL. The mountains also prevent straight roads, so down shifting for corners is required, if not also rather desirable when driving an E30 . So it's of no surprise to me that my clutch is going.

Also, I've had problems shifting 2nd to 3rd when winding up 2nd for a freeway on ramp. I'm positive it's the clutch, unless there is another reason that after such a shift that my RPM's would stay at 4500, feel no acceleration, and that letting off the gas let's the RPM drop without a speed change until I feel a "catch" after which I am able to accelerate the car again.

I'm hoping that the "durability" of the E30 clutch will allow it to hold together a bit longer. Flooring it in any gear doesn't cause it to slip, so it hasn't gotten that bad yet.

QuoteEarendilI've had problems shifting 2nd to 3rd when winding up 2nd for a freeway on ramp. I'm positive it's the clutch, unless there is another reason that after such a shift that my RPM's would stay at 4500, feel no acceleration, and that letting off the gas let's the RPM drop without a speed change until I feel a "catch" after which I am able to accelerate the car again.

I'm hoping that the "durability" of the E30 clutch will allow it to hold together a bit longer. Flooring it in any gear doesn't cause it to slip, so it hasn't gotten that bad yet.

That's odd. That is exactly what it feels like when the clutch slips, but from your description it sounds more like something is sticking in the clutch action causing it to slip only sometimes.

If it were simply a worn out clutch disk, then you'd first notice it slipping when the engine is working hard in the highest (5th) gear. The clutch sees the highest strain in the top gears. Cruising on the highway or climbing a hill in 5th gear, if you give it lots of throttle it would feel like you're getting wheel spin. Revs go up, but speed stays the same.

As the clutch lining wears thinner you'd then start noticing it slipping in 4th as well, and 3rd, eventually even 2nd. Once it starts slipping all the way down in 1st gear, then you've got a big problem as it's going to be near impossible to get the car moving.

You say you notice it slipping when upshifting from 2nd to 3rd. But have you ever noticed it in 5th gear?? If it's just a worn out clutch and already slipping in 3rd, then you should be able to break the clutch loose pretty much anytime in 5th simply by standing hard on the throttle.

QuoteFerdinand
That's odd. That is exactly what it feels like when the clutch slips, but from your description it sounds more like something is sticking in the clutch action causing it to slip only sometimes.

If it were simply a worn out clutch disk, then you'd first notice it slipping when the engine is working hard in the highest (5th) gear. The clutch sees the highest strain in the top gears. Cruising on the highway or climbing a hill in 5th gear, if you give it lots of throttle it would feel like you're getting wheel spin. Revs go up, but speed stays the same.

As the clutch lining wears thinner you'd then start noticing it slipping in 4th as well, and 3rd, eventually even 2nd. Once it starts slipping all the way down in 1st gear, then you've got a big problem as it's going to be near impossible to get the car moving.

You say you notice it slipping when upshifting from 2nd to 3rd. But have you ever noticed it in 5th gear?? If it's just a worn out clutch and already slipping in 3rd, then you should be able to break the clutch loose pretty much anytime in 5th simply by standing hard on the throttle.

I've only noticed it when making poor (i.e. quick) shifts. The first time I noticed it was when down shifting 5th to 4th and poorly rev matched, and then stood on the gas too soon (I needed to make a quick accelerating lane change). So the RPMs shot up, but went up past where 4th gear should have sat at that speed. I let off the gas, the revs dropped to the proper place, and the gas medal was again connected to the road.

Recency I've noticed it shifting 2nd to 3rd. 2nd is the only gear I ever have a need (or at least a reasonable excuse) to spin up. I'm a fairly quick shift, and often can back off the clutch before the RPMs drop down naturally to the 3rd gear speed. Again, if I end up getting on the gas too soon, the clutch doesn't catch.

At first I thought it was just an absolutely terrible shift. It was late at night and I was tired. Then the cylinders failed a day later, and I was hopeful that something in the system was causing a delay in how long it took the clutch to re-engage.

Basically, the clutch has only ever slipped on me when I've failed to let static friction on the plates take over first. When it's only kinetic friction, I can over power the clutch plate with the gas. Since Static friction has more force than kinetic, this doesn't surprise me too much. In other words, if I were to try and do a drag race start, and dump the clutch, I would predict that the clutch would spin, and the wheels wouldn't make a squeak. But I've never tried that and am not starting now

QuoteEarendilBasically, the clutch has only ever slipped on me when I've failed to let static friction on the plates take over first. When it's only kinetic friction, I can over power the clutch plate with the gas.

So maybe it's not worn too much yet and it's only happening on bang shifts. Obviously, it if does slip like this, you should back off right away and let it hook up with static friction. Otherwise you're going to fry it for sure.

But eventually it will start slipping in 5th gear, when enough engine torque is applied to break loose even the static friction. When the engine is working really hard, like trying to climb a hill in 5th gear, that's when it should start slipping. At the other end of the scale, in 1st gear, the engine isn't working that hard to accelerate the car so the clutch is much less likely to slip in 1st.

The fact that you haven't noticed it slipping in 5th, but only on fast shifts, suggests the clutch isn't engaging smoothly. It seems to be binding somehow and the pressure plate is sometimes not applying full pressure to clamp the clutch plate against the flywheel.

Even if the hydraulic circuit, either master or slave cylinder, aren't 100%, that shouldn't affect the clutch engagement. If it's a hydraulic issue, you'd see that as a problem disengaging the clutch, i.e. foot on clutch, pedal is soft or goes to the floor without disengaging the clutch.

The clutch pressure plate is humungously strong. Regardless of whatever issues a leaky hydraulic circuit may have trying to disengage the clutch, the clutch should always be able to come back by itself to fully engaged.

Either the clutch plate is worn just thin enough to cause the symptoms you're seeing now, but not yet worn enough to slip in 5th gear, or you need to grease the splines that the release bearing slides on, or the pressure plate is buggered, or...

The only way to find out for sure is to pull the transmission and have a look at what's going on in the bell housing. Don't leave it too long though. If it is slipping at all, it's most likely that it's simply just a worn out clutch plate. That happens. But, as the lining wears away, it exposes the rivets holding the clutch lining, and then the rivets carve away at your flywheel. Instead of just replacing the clutch, eventually you'll be looking at a new flywheel too.

You've already tackled much tougher jobs. Pulling the transmission isn't all that difficult. It's not fun, but not nearly as nasty as an oilpan gasket, or broken valve rockers. The only tricky bit is centering and aligning the clutch plate with the hole in the flywheel, before clamping it in place with the pressure plate. If it's not perfectly aligned you'll have a bugger of a time trying to get the nose of the transmission input shaft back in there while trying to lift the transmission into place. Do yourself an enormous favour and spend the extra few bucks to buy or rent a clutch alignment tool. Otherwise, bite the bullet and pay someone to replace the clutch for you. It's not going to fix itself.

QuoteFerdinand
The fact that you haven't noticed it slipping in 5th, but only on fast shifts, suggests the clutch isn't engaging smoothly. It seems to be binding somehow and the pressure plate is sometimes not applying full pressure to clamp the clutch plate against the flywheel.

When you say it "suggests", do you think there is a better than 50% chance it's not just a worn clutch?

QuoteEven if the hydraulic circuit, either master or slave cylinder, aren't 100%, that shouldn't affect the clutch engagement. If it's a hydraulic issue, you'd see that as a problem disengaging the clutch, i.e. foot on clutch, pedal is soft or goes to the floor without disengaging the clutch.

I can see that now. Before doing the work and reading up on it, I thought (or hoped) there might be a way to pressure the system that would not lose pressure correctly or quickly.

QuoteEither the clutch plate is worn just thin enough to cause the symptoms you're seeing now, but not yet worn enough to slip in 5th gear, or you need to grease the splines that the release bearing slides on, or the pressure plate is buggered, or...

Could tossing a bunch of hydrolic fluid into the bell housing cause or accelerate any of the potential problems? I've never cracked open a transmission before so I'm not exactly sure what's behind that case of metal. Even though I think the Master cylinder is the one that catastrophiclly failed, the slave was also all buggered up. I suspect it was leaking fluid into the bell housing.

QuoteThe only way to find out for sure is to pull the transmission

Doh!

Quoteand have a look at what's going on in the bell housing. Don't leave it too long though. If it is slipping at all, it's most likely that it's simply just a worn out clutch plate. That happens. But, as the lining wears away, it exposes the rivets holding the clutch lining, and then the rivets carve away at your flywheel. Instead of just replacing the clutch, eventually you'll be looking at a new flywheel too.

You've already tackled much tougher jobs. Pulling the transmission isn't all that difficult. It's not fun, but not nearly as nasty as an oilpan gasket, or broken valve rockers. The only tricky bit is centering and aligning the clutch plate with the hole in the flywheel, before clamping it in place with the pressure plate. If it's not perfectly aligned you'll have a bugger of a time trying to get the nose of the transmission input shaft back in there while trying to lift the transmission into place. Do yourself an enormous favour and spend the extra few bucks to buy or rent a clutch alignment tool. Otherwise, bite the bullet and pay someone to replace the clutch for you.

My problem is that I work alone, in the elements, on jack stands. Having to get it done in a weekend so I can drive to work on Monday is just the icing. If any one of those things improves I'd be more inclined to do work. I did the Clutch cylinders using a foam pad to keep half way dry. Turns out it's great for the back and knees too
How feasible do you think the transmission is as a solo job? I did the Drive shaft solo, which was on the boarder of tolerable. I'm guessing the transmission weighs substantially more.

I'll give it a little longer. Hopefully I can ride it until I feel 5th gear slipping. I'm contemplating getting a more reliable daily driver. Even if younger cars break just as often, they do so in more predictable ways.I'd hate to turn into one of those Americans with 2 cars, but without public transportation I need a way to get to work. At the very least I can let these kinds of projects extend through the weekend if I had a secondary vehicle...

QuoteEarendilHow feasible do you think the transmission is as a solo job? I did the Drive shaft solo, which was on the boarder of tolerable. I'm guessing the transmission weighs substantially more.

You guess correctly. I've dropped transmissions solo, and it absolutely requires the use of a floor jack to bear the weight of the transmission, and to raise and lower it gently. It's easier with two people, but it's doable solo. It's also possible to do it in a weekend, but you'll need lots of time and a source of light. I don't think I'd want to do it outside. You would also need a plan B for getting to work Monday if the inevitable happens and you can't get it all back together. That, and a way of getting to the parts store over the weekend for whatever it is you forgot you needed for the job. (At least, that's the way it always works for me. )

I'd recommend doing the transmission removal on a hoist, that way it is really easy when there's another pair of hands to help. That is how I did a clutch replacement on my iS, took 4 hours to do (the other guy had done it before, for me it was my first time).

For the clutch alignment, you can make your own tool, with a broomstick or something similar. If it doesn't fit the clutch spline, you can make the diameter larger by winding some paper tape around until it fits.

Now that I think of it, I had trouble on my VW Transporter clutch when the transmission input shaft sealing started leaking. It slipped in higher gears and at first there was no leakage visible either. But in this case, there was no pedal trouble involved, so I guess this is not the case with your transmission.